1. Technical Field
The disclosure is related to seismic exploration for oil and gas, and more particularly to determination of the positions of subsurface reservoirs.
2. Description
Expensive geophysical and geological exploration investment for hydrocarbons is often focused on acquiring data in the most promising areas using relatively slow methods, such as reflection seismic data acquisition and processing. The acquired data are used for mapping potential hydrocarbon-bearing areas within a survey area to optimize exploratory or production well locations and to minimize costly non-productive wells.
The time from mineral discovery to production may be shortened if the total time required to evaluate and explore a survey area can be reduced by applying geophysical methods alone or in combination. Some methods may be used as a standalone decision tool for oil and gas development decisions when no other data is available.
Geophysical and geological methods are used to maximize production after reservoir discovery as well. Reservoirs are analyzed using time lapse surveys (i.e. repeat applications of geophysical methods over time) to understand reservoir changes during production. The process of exploring for and exploiting subsurface hydrocarbon reservoirs is often costly and inefficient because operators have imperfect information from geophysical and geological characteristics about reservoir locations. Furthermore, a reservoir's characteristics may change as it is produced.
The impact of oil exploration methods on the environment may be reduced by using low-impact methods and/or by narrowing the scope of methods requiring an active source, including reflection seismic and electromagnetic surveying methods. Various geophysical data acquisition methods have a relatively low impact on field survey areas. Low-impact methods include gravity and magnetic surveys that may be used to enrich or corroborate structural images and/or integrate with other geophysical data, such as reflection seismic data, to delineate hydrocarbon-bearing zones within promising formations and clarify ambiguities in lower quality data, e.g. where geological or near-surface conditions reduce the effectiveness of reflection seismic methods.